#!/usr/bin/env python3
# Copyright (c) 2016 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Encode and decode BASE58, P2PKH and P2SH addresses."""

from .script import hash256, hash160, sha256, CScript, OP_0
from .util import bytes_to_hex_str, hex_str_to_bytes
import binascii

chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'

def byte_to_base58(b, version):
    result = ''
    str = bytes_to_hex_str(b)
    str = bytes_to_hex_str(chr(version).encode('latin-1')) + str
    checksum = bytes_to_hex_str(hash256(hex_str_to_bytes(str)))
    str += checksum[:8]
    value = int('0x'+str,0)
    while value > 0:
        result = chars[value % 58] + result
        value //= 58
    while (str[:2] == '00'):
        result = chars[0] + result
        str = str[2:]
    return result

# TODO: def base58_decode
def base58_to_byte(v, length):
  """ decode v into a string of len bytes
  """
  __b58chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
  __b58base = len(__b58chars)
  long_value = 0
  for (i, c) in enumerate(v[::-1]):
    long_value += __b58chars.find(c) * (__b58base**i)

  result = ''
  while long_value >= 256:
    div, mod = divmod(long_value, 256)
    result = chr(mod) + result
    long_value = div
  result = chr(long_value) + result

  nPad = 0
  for c in v:
    if c == __b58chars[0]: nPad += 1
    else: break

  result = chr(0)*nPad + result
  if length is not None and len(result) != length:
    return None

  hexresult = binascii.hexlify(bytes(result.encode('latin-1')))

  version = int(hexresult[0:2], 16)
  hsh = hexresult[2:42]
  checksum = hexresult[42:]
  return (version, hsh, checksum)

def keyhash_to_p2pkh(hash, main = False):
    assert (len(hash) == 20)
    version = 58 if main else 120
    return byte_to_base58(hash, version)

def scripthash_to_p2sh(hash, main = False):
    assert (len(hash) == 20)
    version = 50 if main else 110
    return byte_to_base58(hash, version)

def key_to_p2pkh(key, main = False):
    key = check_key(key)
    return keyhash_to_p2pkh(hash160(key), main)

def script_to_p2sh(script, main = False):
    script = check_script(script)
    return scripthash_to_p2sh(hash160(script), main)

def key_to_p2sh_p2wpkh(key, main = False):
    key = check_key(key)
    p2shscript = CScript([OP_0, hash160(key)])
    return script_to_p2sh(p2shscript, main)

def script_to_p2sh_p2wsh(script, main = False):
    script = check_script(script)
    p2shscript = CScript([OP_0, sha256(script)])
    return script_to_p2sh(p2shscript, main)

def check_key(key):
    if (type(key) is str):
        key = hex_str_to_bytes(key) # Assuming this is hex string
    if (type(key) is bytes and (len(key) == 33 or len(key) == 65)):
        return key
    assert(False)

def check_script(script):
    if (type(script) is str):
        script = hex_str_to_bytes(script) # Assuming this is hex string
    if (type(script) is bytes or type(script) is CScript):
        return script
    assert(False)
